Gear pump

ABSTRACT

A gear pump, particularly for pumping gasoline under high pressures, comprises two intermeshed gears on substantially parallel shafts and an annular casing of substantially the same thickness as the gears surrounding the periphery of the gears and held between two casing covers arranged on respective sides of the gears which carry bores for receiving and rotatably supporting the shafts. The gears of the pump each include a bore having a raised or crowned central portion which bear on the gear mounting shaft and they are secured for rotation with the shaft by a bolt or connecting pin which extends diametrically through the shaft and engages at its projecting ends in cross-grooves defined in the gear bores. The gears are held against lateral displacement by lock washers secured to the shaft on each side of the gear.

United States Patent Haupt GEAR PUMP [72] Inventor: Fritz Haupt, Zurich, Switzerland [73] Assignee: Maag Gear Wheel & Machine Co.,

Ltd., Zurich, Switzerland [22] Filed: March 4, 1970 [21] Appl.No.: 16,310

[52] US. Cl. ..418/178, 418/179, 418/182, 418/206 [51] Int. Cl ..F01c 17/00, F03c 3/00, F04c 15/00 [58] Field of Search ..418/178, 179, 205, 206, 182

[56] References Cited UNITED STATES PATENTS 3,174,435 3/1965 Sisson et al. ..418/206 3,544,244 12/1970 Haupt ..418/179 1,834,754 12/1931 Whaley ..418/206 X 1,938,566 12/1933 Birkigt .;.309/3 1,943,491 l/l934 Sieper ..418/206 2,014,932 9/1935 Hallett ..418/179 X 2,619,040 11/1952 Maisch ..418/206 X 2,626,570 l/l953 Armington et a1 ..418/74 3 ,028,81 1 4/1962 Rothen meyer ..418/200 [151 3,704,968 [4 1 Dec. 5, 1972 FOREIGN PATENTS OR APPLICATIONS 265,576v 8/ 1927 Great Britain ..413/182 Primary Examiner-Carlton R. Croyle Assistant Examiner-John J. Vrabllik Attorney-McGlew and Toren [57] ABSTRACT A gear pump, particularly for pumping gasoline under high pressures, comprises two intermeshed gears on substantially parallel shafts and an annular casing of substantially the same thickness as the gears surrounding the periphery of the gears and held between two casing covers arranged on respective sides of the gears I which carry bores for receiving and rotatably support- 1 ing the shafts. The gears of the pump each include a bore having a raised or crowned central portion which bear on the gear mounting shaft and they are secured for rotation with the shaft by a bolt or connecting pin which extends diametrically through the shaft and engages at its projecting ends in cross-grooves defined in the gear bores. The gears are held against lateral displacement by lock washers secured to the shaft on each side of the gear.

4 Claims, 3 Drawing Figures PA'TE'NTED DEB 's 1972 SHEET 1 BF 2 wn A 2 9 5 H 3 mm B J m w,

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SUMMARY OF THE INVENTION This invention relates, in general, toa construction of pumps and, in particular, to a new and usefulgear pump particularly for pumping gasoline under high pressure conditions and having two externally toothed gear wheels mounted on two parallel shafts which are secured to the shaft by a pin which extends through the shaft and projects into a cross-groove of the associated gear. a i 1 a The presentgear pumps for gasoline delivery do not permit very high pressures and are susceptible to operating troubles so that they do not provide a long service life with high reliability. Particularly with pumps that are used for the delivery of gasoline, for example, in connection with the injection of gasoline into automotive engines without carburetors, a very high reliability and thus a long service of the pump are important. I a

In the known gear pumps of theabove type the gear wheels are secured by means of adhesives on their shafts in order to ensurean accurate'circular and transverse movement, since high pressures are: required when delivering gasoline in connection with direct gasoline injection without a carburetor. This also requires a high precision in the manufacture of the casing and casing covers. But such a high precision in the machining of these parts can only be achieved for custom models, but not in mass production. In order to avoid this requirement for great precisions in the manufacture of the above mentioned parts, ways had to be found to build nevertheless gear pumpswith maximum safety and high pressures. e i I This is achieved according to the invention'by making the bores of the two gear wheels so-that they are crowned or raised at the center to provide a ringshaped contact between the gear wheel andthe shaft in the center of the gear wheel width. This has the effect that no additional play is required between the lateral bearing surfaces even if the shafts are not absolutely. perpendicular to the lateral bearing surfaces ofthecasing covers or when there is rubbingplanar engagement of the gear end faces on the gear bore. The small wobbling movement of the gears on the shaft required for correcting any defects is made possible by the crowned bore in the gear and this is possible without causing any disadvantages. Preferably the torque between the gears and their shafts is transmitted by a cylindrical pin inserted transversely through the shaft and into two opposing parallel grooves defined in the gear bore.

This arrangement ensures the proper entrainment of the shafts to the gears and the gears are not statically overdefined with the lateralbearing surfaces. The gears adjust themselves automatically corresponding to the tured to provide aclose running peripheral tolerance to the operating gears, and f wherein the gears .IIBVC. crowned shaft mounting bores and are secured to their associated shafts by a cross pin extending through the shaft and engage in a cross groove :of the bore at each end.

A further object of the invention is to provide a pump of good capacity and furability. which is simple in design, rugged in construction and economical to manufacture. a i i For an understanding of the principlesof the invention, reference is made to the.followingdescription of a typical embodiment thereof as illustrated inthe accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view partly in section of a gear pump constructed in accordance with the invention;

FIG. 2 is a partial axial sectional view showing the gear mounting, and Y j FIG. 3 is a section taken on the line III-III of FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing, inparticular, the invention embodied therein comprises a gear pump including an annular casing, generally designated 1, which surrounds two operable interengaged gear elements or gears 2 and 3.

In accordance with the invention the gears 2 and 3 are secured on spaced parallel shafts 4 and 5, respectively, by means of a throughbolt or pin 20 which extends diametrically through the associated shaft 4 or S and is engagedwith each end ina cross-groove .21 of the associated gear. The grooves 21,21 are defined at diametrically oppositelocations in acentrally crowned bore of the groove. Thegear bores are rounded to a central high point or-crown to define a central ringshaped contact 25 between the gear and the shaft.

The gear wheels 2 and 3 are made of a nitriding steel and arenitrided at least on the surfaces, particularly on the teeth and the lateral surfaces. The shafts 4 and 5 are supported by means of needle bearings 6 and 7 and 8 and 9, respectively. The needle bearings 6,7,8 and 9 are supported in respective casing covers 10 and 11. The casing covers 10 and l l'are secured on each side of the casing 1 and abut against the respective sides of the casing 1 and the gear side surfaces. The gear'pumping space is sealed by annular rings or gaskets l2 and 13, which are positioned in grooves defined in the respective covers l0and 11. The gaskets 12 and 13, together with axial gaskets 14 and 15, provide .a liquid seal for thepumping space. The shaft 4 is driventhrough a drive which includes a coupling 16. The whole assembly is secured together by screws or bolts 17 which extend through axial bores 18 and are tightenedin an 3 inlet 19 When the drive shaft is turned in the direction of the arrow indicated on the coupling 16, the gasoline is drawn into the suction tube 19 and pumped out through the outlet which is not shown.

Axial locking between gear wheel 2 and shaft 4 is achieved by a locking washer 22, on each side of the gear wheels 2 and 3. These washers 22 are held in corresponding annular grooves in the associated shafts 4 and 5. Between the locking washers 22 and the gear wheel 2 there is some axial play so as not to hinder wobbling movements between shaft and gear wheel.

The two shafts 4 and 5 have the same diameter for supporting the shafts and for receiving the gear wheels 2 and 3, which means a simplification of the manufacture.

What is claimed is:

l. A gear pump particularly for pumping gasoline, comprising first and second parallel shafts, first and second gears mounted respectively on said first and second shafts for rotation therewith and being substantially of the same thickness and being interengaged for pumping operation, a casing of approximately the same thickness as said gears surrounding said gears, a casing cover secured on each side of said casing and bearing against said casing and rotatably. supporting said parallel shafts, said gears having a bore with a raised central portion defining a ring-shaped contact between said gears and the associated shafts, said shafts including a torque transmission pin extending therethrough and having opposite ends engaged with said gear for connecting said gears for rotation with said shafts, and locking washers on said shafts on each side of said gears the gear thickness being less than the distance between its associated locking washers to allow a predetermined axial play therebetween. I

2. A'gear pump according to claim 1, wherein each of said shafts have the same diameter in respect to the portion thereof which supports said gear and the portions thereof which provide a rotatable bearing support.

3. A gear pump particularly for pumping gasoline, comprising first and second parallel shafts, first and second gears mounted respectively on said first and second shafts for rotation therewith and being substantially of the same thickness and being interengaged for pumping operation, a casing of approximately the same thickness as said gears surrounding said gears, a casing cover secured on each side of said casing and bearing against said casing and rotatably supporting said parallel shafts, said gears having a bore with a raised central portion defining a ring-shaped contact between said gears and the associated shafts, a through pin extending through said first and second shafts, said first and second gears each including a cross-groove defined therein into which the respective ends of the associated pins of said first and second shafts are engaged, said first and'second gears having a bore therethrough with a central crown forming a substantially central ringshaped contact of said gears with the associated first and second shafts, a cross-groove defined through said bore at diametrically opposite locations, a through bolt extending through each of said shafts and engaged in the respective cross-grooves of said first and second gears, and a locking washer carried by said first and second shafts on each side of respective first and second gears for holding said gears in respect to axial movement in relation to the associated first and second shafts the gear thickness being less than the distance between its associated locking washers to allow ,a predetermined axial play therebetween.

4. A gear pump for pumping gasoline at high pressure comprising first and second parallel shafts, first and second nitrided hardened steel gears mounted respectively on said first and second parallel shafts being of substantially the same thickness and being interengaged for pumping operation, a casing of a light metal alloy material and of approximately the same thickness of said gears surrounding said gears and in rubbing contact with the periphery thereof, a casing cover secured on each side of said casing and bearing against said casing and rotatably supporting said parallel shafts, said casing being made of a metal material with running-in properties and at least a lateral surface of said casing covers being in rubbing contact with said gears and having a hard surface of anodically oxidized metal material, said first and second gears each including a bore having a crowned central portion in engagement with the associated shafts, a torque transmission pin extending through said first and second shafts and engaged with said first and second gears respectively, said first and second gears each including a crossgroove for facilitating entry of the associated torque pin from a side thereof, and locking washers carried on such shafts on each side of said gears for preventing withdrawal of the gears from engagement over said torque pin the gear thickness being less than the distance between its associated locking washers to allow a predetermined axial play therebetween. 

1. A gear pump particularly for pumping gasoline, comprising first and second parallel shafts, first and second gears mounted respectively on said first and second shafts for rotation therewith and being substantially of the same thickness and being interengaged for pumping operation, a casing of approximately the same thickness as said gears surrounding said gears, a casing cover secured on each side of said casing and bearing against said casing and rotatably supporting said parallel shafts, said gears having a bore with a raised central portion defining a ring-shaped contact between said gears and the associated shafts, said shafts including a torque transmission pin extending therethrough and having opposite ends engaged with said gear for connecting said gears for rotation with said shafts, and locking washers on said shafts on each side of said gears the gear thickness being less than the distance between its associated locking washers to allow a predetermined axial play therebetween.
 2. A gear pump according to claim 1, wherein each of said shafts have the same diameter in respect to the portion thereof which supports said gear and the portions thereof which provide a rotatable bearing support.
 3. A gear pump particularly for pumping gasoline, comprising first and second parallel shafts, first and second gears mounted respectively on said first and second shafts for rotation therewith and being substantially of the same thickness and being interengaged for pumping operation, a casing of approximately the same thickness as said gears surrounding said gears, a casing cover secured on each side of said casing and bearing against said casing and rotatably supporting said parallel shafts, said gears having a bore with a raised central portion defining a ring-shaped contact between said gears and the associated shafts, a through pin extending through said first and second shafts, said first and second gears each including a cross-groove defined therein into which the respective ends of the associated pins of said first and second shafts are engaged, said first and second gears having a bore therethrough with a central crown forming a substantially central ring-shaped contact of said gears with the associated first and second shafts, a cross-groove defined through said bore at diametrically opposite locations, a through bolt extending through each of said shafts and engaged in the respective cross-grooves of said first and second gears, and a locking washer carried by said first and second shafts on each side of respective first and second gears for holding said gears in respect to axial movement in relation to the associated first and second shafts the gear thickness being less than the distance between its associated locking washers to allow a predetermined axial play therebetween.
 4. A gear pump for pumping gasoline at high pressure comprising first and second parallel shafts, first and second nitrided hardened steel gears mounted respectively on said first and second parallel shafts being of substantially the same thickness and being interengaged for pumping operation, a casing of a light metal alloy material and of approximately the same thickness of said gears surroundinG said gears and in rubbing contact with the periphery thereof, a casing cover secured on each side of said casing and bearing against said casing and rotatably supporting said parallel shafts, said casing being made of a metal material with running-in properties and at least a lateral surface of said casing covers being in rubbing contact with said gears and having a hard surface of anodically oxidized metal material, said first and second gears each including a bore having a crowned central portion in engagement with the associated shafts, a torque transmission pin extending through said first and second shafts and engaged with said first and second gears respectively, said first and second gears each including a cross-groove for facilitating entry of the associated torque pin from a side thereof, and locking washers carried on such shafts on each side of said gears for preventing withdrawal of the gears from engagement over said torque pin the gear thickness being less than the distance between its associated locking washers to allow a predetermined axial play therebetween. 